Yeasts such as C. albicans are often present in the mucosa of healthy people in whom they usually cause no specific disease or symptom. When the body is weakened, the yeasts proliferate and pass into the blood system, in which case reference is made to invasive or systemic infection. In the case of C. albicans, 40% of candidaemias (fungaemias caused by C. albicans) are fatal in human beings. Invasive fungal diseases (IFD) or invasive fungal infections are common, serious hospital disorders. Despite effective treatments, the costs of which are increasingly difficult for hospitals to carry, the morbidity of the IFD is not falling. Conventional mycology methods (isolation/identification) are often defective as risk-free access to the localised sites of infection in the patient for sampling the fungus is often impossible. Blood cultures are also negative in almost half of cases of IFD. So-called molecular biology methods (PCR) do not resolve these problems. In addition, it has now been established that early introduction of anti-fungal treatment—based on a diagnosis—influences patients' survival. Amongst the additional or alternative diagnostic methods to conventional mycology, the use of detection methods for circulating glycans (i.e. fungal glycans contained in the serum of infected patients) in patient sera is now recognised by clinicians. These glycans come from the wall of the microcetes or their precursors and can be detected with commercial immunological tests. As such, the Platélia® Candida Antigen test can detect mannans and galactamannans originating from Candida and Aspergillus respectively. Biochemical kits such as those marketed under the brand Fungitell®, for example, can detect glucans, which are common to candida and Aspergillus. 
Each of the two types of “kit” listed above contains many different reagents and internal standards. The need to construct calibration curves into each batch leads to increased consumption of reagents, particularly when intended to test serum. This need for calibration can sometimes lead to investigations not being performed for financial reasons (because of insufficient reagents). It is, for example, difficult with Fungitell®, to justify the use of nine wells for calibration and to monopolise a technician for half a day to test one serum. These tests also require access to specifically programmed autoanalysers and have interfaces with the informatics system, which further complicates their urgent practical uses on a single patient basis, when they should be able to respond to a request for them as soon as possible.
All of these tests are therefore particularly demanding in terms of time or reagents. In addition, they produce a certain number of false positive results which interfere with the diagnosis. This is particularly true for biochemical measurement of glucan(s) which are interfered with by the presence of haemoglobin (sera which are haemolysed when collected) or the frequent metabolic abnormalities in patients at risk of IFD, such as hypertriglyceridaemia, or the presence of bilirubin or hypoproteinaemia.
Finally, false positive results in patients hospitalised in intensive care with multiple infections with organisms other than fungi has been reported on several occasions. The type of mechanisms in false positive reactions in detecting the P-D-glucans is still unknown as the substances which circulate in these patients' sera have not been characterised on a molecular basis. Because of the existence of these false positive results, some patients who would not require any treatment are given antifungal antibiotic therapy, which prolongs their hospital stay. In the case of false negative results, which are also seen, the interpretation is made that the infection is not fungal but bacterial, and the patient is given antibacterial antibiotic therapy, which is harmful and may be fatal.
In addition, the Fungitell® kit uses blood from the limulus, an animal which is beginning to become rare and at present, it is not possible to farm limuli. They are therefore captured in their natural environment. A sample of blood is taken from the limuli before they are releasing, and 20% of the limuli which are released do not survive.